Integrated circuit dies that use different voltages are well known in the art. Referring to FIG. 1 there is shown a block diagram of a flash (non-volatile) memory integrated circuit die 10 of the prior art. The flash memory circuit die 10 comprises a flash memory array 100, having a plurality of flash memory cells arranged in a plurality of rows and columns. A microcontroller 20 controls the operation of the flash array 100 through an address bus, a data bus and a control bus. Finally, a mixed IP circuit 30 controls both the microcontroller 20 and the array 100 through a mixed signal bus. In a typical operation, the microcontroller 20 is supplied with a voltage source of 3.0 volts, while the flash array 100 is supplied with a voltage source of 1.8 volts. The 1.8 volt source is generated by the mixed IP circuit 30 using a DC-DC converter based upon an externally supplied 3.0 volt source. In addition, the externally supplied 3.0 volt source is also supplied to the microcontroller 20.
Referring to FIG. 2 there is shown a schematic block level circuit diagram 60 of a portion of the flash memory circuit die 10 shown in FIG. 1. The circuit diagram has a die pad 21 connected through bond wire 51 to a bond pad 41 for receiving the externally supplied 3.0 volts. The externally supplied 3.0 volts is then supplied in the die 10 to IO buffer circuit 36, and to other well known circuits, such as TTL circuit 34 (converting input signal voltage level to CMOS voltage level), POR3V circuit 32 (detecting Vdd reaching a pre-determined voltage level), and other circuits not shown. These circuits require 3.0 volts for operation. The 3.0 volt source is also supplied to a DC-DC voltage regulator 30 from which a source of 1.8 volts is generated. The 1.8 volt source is then supplied to other parts of the die 10, described hereinabove, such as the flash memory array 100.
It should be noted that in the prior art, when the memory circuit die 10 is operational, power from the externally supplied 3.0 volts is supplied to the portion of the die 10 requiring 3.0 volts and is transformed by the DC-DC regulator and supplied to the 1.8 volt circuits, at all times, even if not all the circuits requiring the power is operational. For example, after the microcontroller 20 has sent address, data and control signals to the flash memory array 100, the microcontroller 20 need not be powered up, and further only the flash array 100 needs to be powered such as during long chip erase operation for flash memory. Or certain circuit blocks (not shown) inside the flash memory 100 need not be powered during certain chip operation such as during erase or programming operation, read circuits can be on standby and during read operation, erase and programming circuits can be on standby. Reducing and/or eliminating power to portions of the circuit in the die 10 that do not require power can reduce the total power requirements of the integrated circuit die 10.